AJP - Gastrointestinal and Liver Physiology, Vol 240, Issue 1 76-G84, Copyright © 1981 by American Physiological Society
Histamine regulation of adenylyl cyclase of enriched rat gastric parietal cells
W. J. Thompson, L. K. Chang and G. C. Rosenfeld
Rat gastric parietal cells were isolated to 90% or greater purity by
discontinuous gradient ultracentrifugation in sucrose-Ficoll. Adenylyl
cyclase activity was initiated by histamine in the presence of 5'-guanylyl
imidodiphosphate, but not by pentagastrin or acetylcholine. The
concentration of histamine needed for half-maximal activation of adenylyl
cyclase was 38 microM. The histamine H2-receptor antagonist, metiamide,
inhibited histamine (100 microM) activation with a Ki of 0.9 microM. The
effects of other histamine agonists and antagonists suggest that presence
of H2-type histaminic receptors on parietal cells. Adenylyl cyclase
activity was also stimulated by isoproterenol, norepinephrine, and
epinephrine, but not by methoxamine. Half-maximal activation by
isoproterenol occurred at 0.5 microM. Propranolol, but not phentolamine,
prevented activation by these agents, indicating the presence of
beta-adrenergic receptors on parietal cells. Prostaglandins E2 stimulated
adenylyl cyclase of partially purified (30%), but not the enriched (90%),
parietal cell populations.
